1. Field of the Invention
The invention relates to improving the development of biological tissues by the increased uptake of essential polyvalent metals, and more particularly to a synergistic composition containing said metals in a chelated form and method of preparation therefor, the composition having a significantly greater effect on development than the components of the composition chelated.
2. The Prior Art
The presently known essential polyvalent metals in animal nutrition and biological development are calcium, magnesium, zinc, iron, manganese, copper and cobalt. There is also evidence that other elements such as selenium may have significant, if not essential, influence on biological activity. The present invention contemplates the use of the mentioned metals, including selenium and other biologically important polyvalent minerals in the form of metal chelates.
The term "chelate" is stated in Webster's Seventh New Collegiate Dictionary, 1965, as being derived from the Greek chele meaning "claw" and is defined as "of relating to, or having a cyclic structure usually containing five or six atoms in a ring in which a central metallic ion is held in a coordination complex."
In connection with the above definition, metal chelates are herein defined to mean a metal atom attached by more than one donor atom of a ligand in such a manner as to form a heterocyclic ring by coordination complex. A ligand is herein defined to mean molecules of hydrolyzed protein and carbohydrates which are capable of functioning as the donor partner in one or more coordinate bonds. In other words, the ligand is electron rich and/or proton deficient. Ligands having two or more atoms which can simultaneously serve as donors are sometimes called polydentate ligands. Polydentate ligands whose structures permit the attachment of two or more donor sites to the same metal ion simultaneously, thus closing one or more heterocyclic rings, are called chelate ligands. In this specification, the terms chelate ligand an ligand will be used interchangeably and will preferably be referred to as ligand.
From the above it is apparent that a ligand must have available electrons in order to react with the metal ion to form a coordination complex or chelate. Obviously, the more acidic a solution is the more protons will interfere or compete for electrons and the less readily a chelate will form. Therefore, in the case of protein hydrolysates, i.e., polypeptides, peptides and naturally occurring amino acids the alpha amino groups (--NH.sub.2) should be free from interfering protons (NH.sub.3.sup.+) and the carboxylic acid groups should have the protons removed to form carboxy (.crclbar.COO.sup..crclbar.) groups. This is a situation which occurs when the pH is more basic than the isoelectric point of the particular molecule in question. While each molecule has its own isoelectric point or zwitter ionic state it is not possible to have a stated isoelectric point for a group of different molecules such as protein hydrolysates, and thus the terms must be described more functionally, i.e., the mixture must be sufficiently basic that interfering protons are removed from the protein hydrolysate ligand. The same reasoning will also apply to carbohydrate ligands whether in the form of a polysaccharide such as starch, a di- or trisaccharide, or a monosaccharide. It is to be understood that when carbohydrate or polysaccharide hydrolysis products are referred to a monosaccharide is the smallest amount meant since monosaccharides cannot be hydrolyzed to simpler sugars. See, for example, Harrow-Mazur Textbook of Biochemistry, Page 8, 7th Edition 1958.
According to the present invention, it has been found that minerals when administered to biological organisms in chelated form improve the growth rate and/or tissue mineral uptake in the organism. While the precise mechanisms involved and reasons therefor are not yet known with certainty, it is presently believed that improved growth and/or metal uptake result from administering the metal chelates in biologically available form. Metals are mobilized in biological organisms through the formation of metal chelates, an if the metabolism of the organism does not readily facilitate chelate formation, metal assimilation and transport may be inhibited.
Metal chelates are superior to inorganic metal compounds in facilitating metal absorption and transport because many animals or plants will have an inherent defect which inhibits natural endogenic synthesis of metal complex. When one or more metal chelates are provided, the essential or polyvalent metals are introduced into the system in a readily assimilable form and thus are immediately available to bring about metabolic stimulation.
Although the use of metal proteinates, i.e., chelates of hydrolyzed protein for increasing the essential metal content of tissues is known, for example, see copending patent application Ser. No. 739,141, filed June 24, 1968, the formation and use of a synergistic composition of at least two different metal chelates having hydrolyzed protein and carbohydrate ligands to affect biological development in surprising magnitude has heretofore been unknown.